crunch: resolution – R documentation

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resolution

Methods for Datetime variable resolutions

Description

Datetime data has a "resolution", the units of the values. resolution() exposes that property and resolution<- lets you set it. "Rollups" are a way of binning datetime data into meaningful units. rollup() lets you create an expression that you can query with. Datetime variables also have a rollupResolution() attribute that is the default resolution they will roll-up to, if not specified in rollup(); rollupResolution<- lets you set that.

Usage

resolution(x)

resolution(x) <- value

rollup(x, resolution = rollupResolution(x))

rollupResolution(x)

rollupResolution(x) <- value

Arguments

`x`	a Datetime variable
`value`	a resolution string. Valid resolutions in Crunch are `c("Y", "Q", "M", "W", "D", "h", "m", "s", "ms")`. `NULL` is also valid for `rollupResolution<-` but not for `resolution<-`.
`resolution`	Same as `value`, in `rollup()`. This may be `NULL`, in which case the server will determine an appropriate resolution based on the range of the data.

Details

Note that resolution is a property of the data while rollupResolution is metadata. Setting resolution alters the column data, and if setting a more coarse resolution (e.g. going from "s" to "m"), it cannot be reversed. Setting rollupResolution is non-destructive.

Value

resolution() and rollupResolution() return the resolution string for datetime variables, NULL otherwise. The setters return the variable entity after modifying the state on the server. rollup() returns a CrunchExpr expression.

Examples

## Not run: 
resolution(ds$starttime)
## [1] "ms"
resolution(ds$starttime) <- "s"
rollup(ds$starttime)
rollup(ds$starttime, "D")
rollupResolution(ds$starttime) <- "D"
crtabs(~ rollup(starttime), data = ds)

## End(Not run)

crunch

Crunch.io Data Tools

v1.28.0

LGPL (>= 3)

Authors

Greg Freedman Ellis [aut, cre], Jonathan Keane [aut], Mike Malecki [aut], Neal Richardson [aut], Gordon Shotwell [aut]

Initial release